NorthStar 951X Installation Manual page 37

SECTION TWO - Installing the unit
Another major concern, precipitation static (called "P-static"), must be
addressed when installing the differential antenna. P-static generally
appears only during rain or snow; consequently, it can easily be over-
looked during installation. Much like a loran antenna, the effects of
P-static are minimized if the differential antenna is mounted so that it
isn't the highest metallic object on the vessel. The highest metal object
acts much like a lightning rod, attracting tiny static discharges in the
atmosphere. If the differential receiver antenna is the highest object,
these discharges can totally override the differential signals and cause
poor operation in bad weather. The optimum antenna location is high
and clear for fair-weather operation, but below the top of a metal mast or
other antenna for best foul-weather operation. On sailing vessels, the
ACU could be mounted on top of a low mast, or on the stern rail if no
other suitable location is available.
The 8410 differential receiver ACU can be mounted on a standard marine
antenna mount (one inch diameter, 14 threads per inch).
For special applications involving serious grounding problems, or where
optimum portability is required, you can use the AN205-P combination
GPS/DGPS antenna; for details, see "Installing the AN205-P antenna"
starting on page 19.
951/952 INSTALLATION MANUAL Revision B Page 27
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